1. Field of the Invention
This invention relates to a liquid propellant gun having an annular piston for regenerative injection for launching projectiles of different masses at different respective velocities.
2. Art Background of the Invention
Guns having annular pistons for regenerative injection of liquid propellant from a pumping chamber into a combustion chamber are shown in several patents, such as:
U.S. Pat. No. 4,745,841 issued to I. K. Magoon et al on May 24, 1988;
U.S. Pat. No. 4,693,165 issued to I. K. Magoon et al on Sept. 15, 1987;
U.S. Pat. No. 4,586,422 issued to I. K. Magoon et al on May 6, 1986;
U.S. Pat. No. 4,523,508 issued to R. E. Mayer et al on June 18, 1985; and
U.S. Pat. No. 4,341,147 issued to R. E. Mayer on July 27, 1982.
Each of these guns is designed to shoot a particular projectile having a respective mass at a desired respective velocity. Other guns, such as those intended to be carried by tanks, must be designed to fire a variety of projectiles, each having a different mass and desired respective velocity. The two currently popular families of projectiles are: (i) the High Explosive Anti-Tank (HEAT) projectile, and the Armor Piercing Fin Stabilized Discarding Sabot (APFSDS) projectile. These projectiles differ significantly in mass and desired muzzle velocity. The APFSDS projectile relies on its terminal kinetic energy to itself penetrate the armor of its target and, therefore, requires the maximum possible muzzle velocity. The HEAT projectile relies on a shaped charge of high explosive to generate an aperture in the armor of the target and is significantly heavier than the equivalent caliber APFSDS projectile assembly. If a gun were optimized to fire the APFSDS projectile assembly at maximum high velocity and the heavier HEAT projectile were fired, and if there were no compensation for the greater mass, then an excessive chamber pressure would be expected, which might provide catastrophic results. This would be due to the higher inertia of the heavier projectile. To enable the firing of a HEAT projectile, in a gun which will satisfactorily fire an APFSDS projectile, at the same, or if desired, a lower chamber pressure, the regenerative rate of injection of liquid propellant into the combustive chamber must be selectively reduced.
Accordingly, it is an object of this invention to provide a gun mechanism which will regeneratively inject liquid propellant into its combustion chamber at selectable different rates.
It is another object to provide a gun mechanism which will regeneratively input liquid propellant into its combustion chamber at a rate which may be selectably varied during the period of injection.
A feature of this invention is a gun having a housing, a main gun barrel, a combustion chamber, a liquid propellant pumping chamber, and valve means for providing a variable orifice injection port intercoupling said pumping and combustion chambers which includes means for controlling the rate of opening of the orifice during the period of injection.